Ma-ai

Ma-ai refers to the critical distance between opponents, a point at which
forces are essentially neutral, but where anything can happen. Fundamental
to ma-ai is "ma," roughly defined as the way something (or someone) moves
through space over time. Many teachers have stated that ma "cannot be
taught," either one has this sense of timing, or one does not. However,
ma can be enhanced and developed through training. An iaidoka (a student
of iaido) who has a good, well-developed sense of ma has an uncanny sense
of time and distance. Combined with a sense of zanshin, it is the difference
between a merely competent practitioner and a great one. As in other traditional
martial art forms, the ma-ai of iaido embodies the concept of the sphere
of protection, but in this case the circle is extended by the use of the
sword.